Vitamin D Supplementation Protects Against Reductions in Plasma 25-hydroxyvitamin D Induced by Open-heart Surgery: Assess-d Trial

Low vitamin D (serum or plasma 25-hydroxyvitamin D (25(OH)D)) is a global pandemic and associates with a greater prevalence in all-cause and cardiovascular mortality and morbidity. Open-heart surgery is a form of acute stress that decreases circulating 25(OH)D concentrations and exacerbates the preponderance of low vitamin D in a patient population already characterized by low levels. Although supplemental vitamin D increases 25(OH)D, it is unknown if supplemental vitamin D can overcome the decreases in circulating 25(OH)D induced by open-heart surgery. We sought to identify if supplemental vitamin D protects against the acute decrease in plasma 25(OH)D propagated by open-heart surgery during perioperative care. Participants undergoing open-heart surgery were randomly assigned (double-blind) to one of two groups: (a) vitamin D (n = 75; cholecalciferol, 50,000 IU/dose) or (b) placebo (n = 75). Participants received supplements on three separate occasions: orally the evening before surgery and either orally or per nasogastric tube on postoperative days 1 and 2. Plasma 25(OH)D concentrations were measured at baseline (the day before surgery and before the first supplement bolus), after surgery on postoperative days 1, 2, 3, and 4, at hospital discharge (5-8 days after surgery), and at an elective outpatient follow-up visit at 6 months. Supplemental vitamin D abolished the acute decrease in 25(OH)D induced by open-heart surgery during postoperative care. Moreover, plasma 25(OH)D gradually increased from baseline to day 3 and remained significantly increased thereafter but plateaued to discharge with supplemental vitamin D. We conclude that perioperative vitamin D supplementation protects against the immediate decrease in plasma 25(OH)D induced by open-heart surgery. ClinicalTrials.gov Identifier: NCT02460211.